On July 25, 2011, about 1245 central daylight time, an amateur-built Gottschalk John 1 “Dominator” gyroplane, N559RD, sustained substantial damage when it landed hard after losing lift during takeoff from runway 33 at the grass ultralight airstrip at the Wittman Regional Airport (OSH), Oshkosh, Wisconsin, during the 2011 AirVenture air show. The private pilot was not injured. The gyroplane was registered to and operated by the pilot as a personal flight under the provisions of the 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed. The gyroplane was departing from the airstrip on a local flight at the time of the accident. The pilot reported that the gyroplane was traveling about 50 – 55 mph during the takeoff roll when he initiated the climb out. He reported that during the climb out over the last one-third of the runway, the gyroplane started to “settle” and it felt like it was being “pushed down.” He reported that the gyroplane was not creating enough lift to clear the trees located near the west end of the runway, and he did not have enough airspeed or altitude to turn around. The gyroplane continued to lose altitude, and the pilot performed a forced landing to a zone that was clear of people and cars. The gyroplane landed hard and subsequently rolled onto its right side. A witness reported that the gyroplane climbed to 75 – 100 feet above the ground. It stalled, descended quickly, impacted the ground, and flipped over on its side. The pilot reported stated, “A stronger engine may have been able to provide enough power to push through the air.” The gyroplane was equipped with a 65-horsepower Rotax 582 engine, and it had a maximum gross weight of 770 pounds. The pilot reported that the takeoff weight for the accident flight was 645 pounds. The pilot reported that there was no mechanical malfunction or failure. The pilot held a private pilot license with single-engine land and helicopter ratings. He had a solo endorsement for gyroplanes. He had a total of 336 flight hours which consisted of 257 hours in a single-engine airplane, 79 hours in helicopters, and 17 hours in the make and model of the accident gyroplane. At 1235, the surface weather observation at OSH was: wind 240 degrees at 5 knots; 10 miles visibility; clear skies; temperature 27 degrees Celsius; dew point 14 degress Celsius; altimeter 29.98.